The present invention relates to a life management system for parts comprising a gas turbine that reach a high temperature when in use due to the combustion gas of very high temperature thereof (hereinafter referred to simply as xe2x80x9chigh-temperature partsxe2x80x9d).
A combustor, nozzle blades, etc., which are the high-temperature parts of the gas turbine, are located in a channel of the combustion gas of a very high temperature, and therefore may suffer damages, such as thermal fatigue cracking creep deformation etc. which break out due to thermal strain induced repeatedly in connection with start-ups and shutdowns of the gas turbine and a high-temperature environment during its steady operation. A gas turbine power-generating unit in which electric power is generated by driving a power generator with rotational output of the gas turbine has merit of an excellent operability compared to other power-generating units.
Therefore, the gas turbine power-generating unit is imposed with severe operating conditions such as Daily Start-up and Shutdown (DSS) and Weekly Start-up and Shutdown (WSS). Operations, such as these DSS and WSS, where the number of start-ups and shutdowns reaches a large value are employed frequently. Especially, because the high-temperature parts of the gas turbine are used under extremely severe conditions, heat-resistant superalloys of nickel base or cobalt base are used for these parts. Although being superalloys, such high-temperature parts are used under conditions close to their critical temperatures, and that there is a variation in operating conditions as described above. Consequently, these parts are likely to suffer damages considerably earlier than other parts.
Therefore, when putting the gas turbine into operation, it is periodically suspended, parts including the high-temperature parts etc. are inspected for the damages, and if necessary a part is repaired or replaced. However, since these parts are made of expensive superalloys, costs required to perform their repairing and replacement inevitably occupy a considerable portion of an overall operational cost. In order to reduce the operational costs, it is important to improve the accuracy of evaluation of remaining lives of these parts and hence aim at rationalizing any standards for repairing and replacement.
Regarding techniques for evaluating the remaining life of the high-temperature parts, for example, in Japanese Published Unexamined Utility Model Application No. 4-27127, proposed are a method and its device for estimating thermal strain induced in members from measurement results of an exhausted combustion gas temperature and estimating their damage. For other methods, in Japanese Published Unexamined Patent Application No. 4-355338, proposed are a method and its device for evaluating the damages by taking in a crack initiation status of a member surface as an image and simulating crack growth using a certain probability model. Further, in Japanese Published Unexamined Patent Application No. 10-293049, proposed is a maintenance management device for the gas turbine that enables its maintenance by means of damage evaluation based on changes of microscopic structure, and crack growth prediction, etc.
In addition to these contrivances, used is a method wherein a sample is taken out of a part to be inspected and then imposed with a destructive test to estimate its damage, and the like. Further, in Japanese Published Unexamined Patent Application No. 10-196403, devised is a life management device for judging necessity of repairing and replacement of each part of the gas turbine based on management of actual data thereof and their evaluated lives and displaying the results.
In applying the above-described methods to a practical use, professional knowledge and design data such as materials data, results of structure analysis, etc. are necessary. Further, it is also important to prolong a period required for these evaluations in order to reduce operational costs necessary for installation maintenance. Further, to improve the accuracy of the evaluation, it is also important to maintain a circumstance where comparison and referencing of damage data of the past can easily be conducted. To do so, it is necessary to construct a database with information comprising a base of the evaluation and put the database into operation. However there is few cases where such information is integrated so as to be served as an available database because a person who installed the gas turbine, person in charge of maintenance management, its designer, etc. are different to one another.
Owing to this, frequently it is likely to be a work requiring a considerable time in existing circumstances to prepare the damage data from results of inspection and evaluate the damage by referring to design data and material data. There is often the case where works necessary for performing, for example, preparation of material data necessary at time of designing, statistical analysis of real component damage data, review of design conditions based on it, etc. become complicated, because databases are not served in such an integrated form that allows various staff members to share information. To solve the difficulties, a remaining-life evaluation device and the life management device as described above have been proposed. However, respective factors in the evaluation, such as investigation of the damage data of a real component, damage analysis, selection of material data, etc. still require professional knowledge, and hence its effective operation is in a difficult situation.
In addition, although conventional methods enable an operator to obtain the damage and the remaining life of an object part, it is also an important task to optimize operation of the gas turbine based on the damage of a part evaluated, in order to reduce operational costs. To achieve this, results of the structure analysis when a loading pattern at time of start-up and shutdown is altered, material data under a condition where repairing is performed, etc. become necessary. However, with current methods, it is difficult to rapidly formulate both prediction of the damage and the remaining life when these conditions are altered and the optimization of operation of the gas turbine with intent to reduce the operational costs consistently.
Therefore, it is the object of the present invention to provide a system capable of rapidly performing the remaining-life management of the high-temperature parts of the gas turbine.
In the present invention, a remaining-life management system for high-temperature parts of the gas turbine is constructed that is capable of using an Intranet and working in that environment.
That is, the remaining-life management system comprises one server system and a plurality of other client systems, wherein the server system manages a program for performing the evaluation of the remaining life and the life management, and each client system has a subprogram for accessing the main database of the server system and entering data thereto.
Further, the remaining-life management system employs such a scheme that the results of the structure analysis under conditions where a load variation pattern of start-up and shutdown is altered and life data of repaired members are saved in a database belonging to the client system dedicated to handling these specially, and any data necessary for the life management are transferred to the server system.
Furthermore, a system configuration of a client-server system is adopted that enables an organic combination of the damage database such as results of regular inspection etc., a structure analysis database, a materials database, etc. so that analytical evaluation of an inverse problem which is necessary to examine a life extending structure can be performed rapidly using real component field data.
The life management is performed based on the evaluation of damage growth such as a crack in each part. In evaluating the crack growth, it is necessary to set several operating parameters such as the combustion gas temperature, the warming temperature, and the operating time for one start-up and shutdown, etc. When these parameters change, stress and strain induced in the members change, and hence the damage growth rate also changes.
If change of the stress etc. due to the change of an operating parameter is analyzed one by one and the life is evaluated based on the results, it takes a considerable amount of time. To circumvent this problem, the damage growth is evaluated beforehand under a condition where each operating parameter is altered and a relationship between the damage growth rate and the amount of alteration of each operating parameter is found, respectively. From those relationships, a rate of change of the damage growth rate when each operating parameter is altered is obtained as an acceleration coefficient or index as compared to that of standard conditions. Using the acceleration coefficients or indexes enable damage growth analysis under arbitrary conditions to be performed rapidly.
Furthermore, the above-described acceleration coefficients are set based on results of the damage analysis using the stress and strain that were found through the regression analysis of data obtained at a regular inspection of the real component or through the structure analysis under conditions with altered operating parameters beforehand.
Using the above damage growth analysis, it is evaluated whether operating parameters can be altered so that the damage growth rate is lowered so much as to enable the period of repairing and replacement to be extended and whether an economic effect can be obtained through that alteration. In addition, change of the damage growth rate due to repairing and coating application is also evaluated and stored, as is the case with the above-described acceleration coefficients. By performing the above-described damage growth analysis plural times, alteration of a time of repairing, a repairing method, a time of coating application, or a time of inspection that can give the largest economic effect are judged and displayed within the limit of a predetermined operation program (i.e. operational mode such as DSS and WSS, a time of inspection, etc.).
By the way, when evaluating the effect of coating, in order to consider the thermal shield effect of coating, a relationship between the stress and strain obtained in the structure analysis under conditions where the heat transfer coefficient of a member surface is changed and the life of the member depending upon thermal boundary conditions obtained from the damage growth analysis, which were stored beforehand, are used.
The evaluation of the damage growth is performed for each part. Results of evaluation for each part is shown on an arrangement drawing of each part. Thus, a person in charge of device management now can grasp damage situation of each part easily.